Semiconductor device fabrication may involve deposition of silicon nitride and silicon oxide films. Such films are used in a variety of applications. For example, silicon nitride films may be used in diffusion barriers, gate insulators, sidewall spacers, encapsulation layers, strained films in transistors, and the like. Silicon oxide films, for example, may be used in self aligned double patterning, and/or quad patterning or other fabrication processes. Conventional techniques for depositing silicon oxide and silicon nitride films are not selective relative to other silicon-containing material on the substrate.